Reply To: Blue water pipe…size?

William Rawle

    I’m in the process of fitting a Thermostatic mixer valve (to cool the water a bit at the hot tap).

    Yes, the pipework is Whale. The internal diameter is 10mm and the external is 15mm (same as 12mm copper) – so the wall is quite thick.

    All the connections on my Dufour 40 are push-fit. I used JG Speedfit for the alterations, which will accept the Whale pipe & copper.

    If you need to use compression fittings (my thermostatic valve connections are compression), I learnt that it is wise to use a short length of copper pipe for the compression joint and use a pushfit to connect the copper to the Whale pipe.

    I thought the thickness of the Whale pipe wall could withstand the pressure of a compression joint. But it doesn’t always make a watertight seal – I had an annoying weep.

    You can get inserts for a 10mm pipe, but that reduces the bore.

    Good Luck